1. Field of the Invention
The present invention relates to a light emitting device and a manufacturing method of the light emitting device, and especially relates to a light emitting device that is capable of suppressing deterioration in characteristics and improving reliability and a manufacturing method of the light emitting device.
2. Description of the Related Art
A light emitting device loaded with a light emitting semiconductor chip is often hermetically sealed with a package with the light emitting semiconductor chip being loaded on a base. However, because hermetical sealing of the light emitting semiconductor chip with a package becomes an obstacle in miniaturizing the light emitting device, there is a case that a light emitting device is desired in which the hermetic sealing with a package is not necessary.
Further, there is a merit in omitting a hermetic sealing step with a package from the viewpoint of reducing the manufacturing cost of the light emitting device. For example, a semiconductor laser device with a light emitting wavelength of 780 nm used in a CD (Compact Disk) or a semiconductor laser device with a light emitting wavelength of 650 nm used in a DVD (Digital Versatile Disk) is loaded in a state in which hermetic sealing called as frame package is not performed when miniaturization is required.
Further, there is a case that the light emitting semiconductor chip is hermetically sealed with a package together with an optical element depending on use. In this case, an adhesive containing an organic substance is used in adhesion of the optical element in the package, for example.
However, in a semiconductor laser device having a light emitting wavelength of about 405 nm that has appeared in recent years, it is known that a deposition containing silicon (Si) and oxygen (O) is formed at the light emitting edge of the semiconductor laser chip and remarkable deterioration in characteristics occurs in the case of hermetically sealing the adhesive containing an organic substance and the semiconductor laser chip in a package (for example, refer to Japanese Patent Laying-Open No. 2004-289010).
A result of actually performing a continuous driving test of the semiconductor laser device in which the adhesive containing an organic substance and the semiconductor laser chip having a light emitting wavelength of about 405 nm were hermetically sealed in a package is shown in FIG. 14. Here, the continuous driving test was performed using an apparatus for the continuous driving test of the semiconductor laser device in a mode of controlling the driving current value so that the light output at a temperature of 75° C. becomes constant at 15 mW (APC mode). As shown in FIG. 14, a large change in the driving current value is seen that is considered to be caused by formation of the deposition onto the light emitting edge of the semiconductor laser chip.
Such formation of the deposition onto the light emitting edge of the semiconductor laser chip occurs in a semiconductor laser device having a light emitting wavelength of 550 nm or less not only by the adhesive containing an organic substance, but also by an organic substance attaching in the manufacturing process of the semiconductor laser device, and induces characteristic deterioration of the semiconductor laser device (for example, refer to Japanese Patent Laying-Open No. 2004-040051).
The phenomenon as described above is a phenomenon that cannot be seen in a light emitting device having a light emitting wavelength of 650 nm or more.